Soil Microbial Ecology

Illinois Wetland Restoration

Riparian wetlands are sites of intense biogeochemical activity and play an important role in decreasing the export of nutrients to downstream ecosystems. Microbial communities control biogeochemical transformations that are important for improving water quality. Increasing our knowledge about the ecology of specific populations that contribute to biogeochemical processes of interest (e.g. denitrification) will help us to better understand the impacts of land use change on microbial communities and their activities. Investigating the environmental factors that control the abundance and activity of these microbial populations will allow elucidation of specific environmental characteristics that are most important to successfully restore the denitrification capacity of wetland ecosystems. This project is a collaboration with Jeff Mathews (Illinois Natural History Survey Center for Wildlife and Plant Ecology; Department of NRES, UIUC) and Dr. Anton Endress (Department of NRES, UIUC).

Biofuels and Sustainability

Perennial crops like switchgrass (Panicum virgatum) and miscanthus (Miscanthus x giganteus) may be used as biofuels to reduce dependence on fossil fuels. In addition, these biofuels produce less CO2 and greenhouse gases than fossil fuels, reduce emissions of sulfur, nitrogen oxides and carbon monoxide, and sequester carbon in agricultural soils. Feasibility of biofuels depends on developing sustainable production systems, particularly those that minimize the need for fertilizer inputs. Sustainability depends on microbial N cycling processes, especially nitrogen fixation.

Miscanthus and switchgrass can harbor microbial populations (endophytes) within the plant roots, stems and leaves. We are investigating these microbial populations, using molecular microbial ecology methods (DNA "fingerprinting", comparative genomics, microarrays) to search for bacterial populations that can contribute to the sustainability of biofuel production. This work is part of the Energy Biosciences Institute at University of Illinois.

Microbial Ecology and Global Change

Agroecosystems influence the flow of nutrients and energy through the biosphere, and are critical to global food supply. These ecosystems are projected to be particularly sensitive to global change scenarios such as rising temperatures and increased atmospheric CO2 concentrations. The response of agroecosystems to global change will be determined, in part, by the response of microbially-mediated soil processes to changes in the quantity and quality of plant root exudates. We are using the University of Illinois SoyFACE platform to explore plant-microbe interactions under elevated CO2. We are interested in examining the response of microbial community structure and function under elevated CO2, and to correlate changes in soil microbial communities to agroecosystem function, nitrogen availability, and greenhouse gas emissions.

Aquatic Microbial Ecology

Microbial ecology is similar to studying the ecology of plants or animals, but bacteria grow much faster, so many generations can be observed for bacteria in just a few weeks or months, rather than years. Like macro-organisms, the microbial community in an ecosystem changes over time, in response to environmental factors. These factors can be chemical or physical factors, meteorological factors, or interactions with other organisms (organisms that serve as a resource, organisms that prey on bacteria, or organisms that compete with bacteria for resources).

Bacterial communities can be considered as a group (biomass or abundance), or can be considered as their composite populations (the different species that make up the community). Different bacteria can have different functions, such as different abilities to transform nutrients, so we are sometimes interested in understanding the factors that influence the dynamics of a specific population.

Microbial food webs

Microbial population dynamics are influenced by drivers acting from outside and from within an ecosystem. At the local scale, freshwater pelagic microbes are strongly influenced by interactions with other organisms such as algae and predators. The Kent lab participates in the North Temperate Lake Microbial Observatory (http://microbes.limnology.wisc.edu) to examine the impact of food web interactions on microbial community structure and function. We are particularly interested in exploring the relationship between communities of primary producers and heterotrophic bacterial communities. We are also exploring bacterial-algal interactions in experimental stream biofilms in collaboration with Walter Hill at the Illinois Natural History Survey.

Aquatic food webs: Exploring the potential of fish diversity as a determinant of ecosystem properties in aquatic food webs

In conjunction with Illinois Natural History Survey collaborators Mike Carey and Dr. David Wahl, who have manipulated fish diversity in experimental ecosystems, the Kent lab is exploring the impact of changes in diversity at higher trophic levels on bacterial community composition and diversity and relating this to ecosystem function.

Microbial Aspects of a Healthy Environment

Microbial ecology may play an important role in a "healthy environment". In addition to providing antigens that may "train" the immune system to generate an appropriate response to harmless agents, a diverse microbial flora (in the environment, or on bodily surfaces such as the skin or gut) may prove to be less "invadable" by harmful organisms. We are exploring these ideas in artificial marine habitats in collaboration with the Shedd Aquarium in Chicago and the Vancouver Aquarium in Vancouver, B.C. We will examine the impact of environmental management on the microbial ecology of aquarium ecosystems, and link observations about the diversity and dynamics of microbial communities to long-term data on animal health in these artificial habitats.

We are also studying the microbial ecology of animal housing facilities. In conjunction with Angela Green in Agricultural and Biological Engineering, we are exploring the microbial aspects of environmental quality in poultry housing.

Microbial Ecology of the Chattooga River: Anthropogenic Impacts and Implications for Human Health

The Chattooga River in the southeastern US is a federally designated "Wild and Scenic River". The Chattooga Watershed contains some of the most scenic and valuable water resources in the region. This resource supports a large recreation industry that attracts 100,000 visitors each year participating in whitewater kayaking, rafting, and other recreational activities. While the river's "Wild and Scenic" status protects the river proper, the water quality in this river can be negatively impacted by tributaries that are not protected by federal guidelines. Degraded water quality may impact the health of visitors recreating on the river, as well as recreation industry workers (e.g. whitewater raft guides). Staphylococcus skin infections are a common occurrence among river rafting guides, however little is known about the source of such infections. Our research uses molecular microbial ecology methods to examine the microbial communities in the Chattooga River and its tributaries, and explores the impact of water quality issues on the health and behavior of recreation workers.